The present invention relates generally to a method and apparatus for identifying half pedal region existing in relationship between a damper pedal and a damper in a keyboard musical instrument including string sets and dampers, as well as a non-transitory computer-readable storage medium storing program instructions for causing a computer to perform such a method.
Typically, keyboard musical instruments, which are constructed to generate a tone in response to striking of a string set (comprising one or more strings), have, for each of keys, a damper that is brought into and out of contact with the corresponding string set. As well known, the keyboard musical instruments are provided with a loud pedal (damper pedal) for controlling behavior of the dampers. Generally, in a depression stroke of the loud pedal (damper pedal), there are three different regions: a “play region (or rest region)” where no influence of depression of the loud pedal is transmitted to the dampers; a half pedal region from a point where reduction of pressing contact force applied from the dampers to the string sets is started to a point where the dampers are brought out of contact with the string sets; and a “string-releasing region” where, following the above-mentioned half pedal region, the dampers are completely spaced from the string sets.
Also known are keyboard musical instruments which can be caused to execute an automatic performance, including pedal operation, by supplying a driving electric current to a solenoid coil to drive a pedal in accordance with performance data. In an automatic performance on such a keyboard musical instrument, it is desirable, particularly in order to enhance reproducibility of the performance, that appropriate control be performed on the loud pedal and the like to provide appropriate pedal operation matching the above-mentioned half pedal region. For example, in performing feedback control etc. of pedal operation based on performance data, it would be important to properly identify the half pedal region and have the identified half pedal region reflected in the control.
Thus, there have heretofore been proposed methods or techniques for accurately and easily identifying a half pedal region and a half point present in that half pedal region. Japanese Patent No. 4524798, for example, discloses a technique for observing driving loads on a pedal to identify a half point of the pedal. Further, Japanese Patent Application Laid-open Publication No. 2007-292921 discloses detecting vibrations of a soundboard to identify a half point of the pedal.
As known, a lifting rail is connected to the loud pedal, and the lifting rail moves vertically upward and downward in response to an operation of the pedal. As the loud pedal is depressed, damper levers are driven to pivot via the lifting rail, so that all of the dampers ascend via damper wires. Thus, damper felts of all of the dampers are brought from a string-contacting state or position (damper-on position) to a non-string-contacting state or position (damper-off position).
As generally known, the “half pedal region” in relationship between the loud pedal and the dampers responsive to an operation of the loud pedal is a concept derived when the dampers of all of the keys are regarded as behaving similarly with respect to a pedal stroke. Namely, till now, the half pedal region of the conventionally-known loud pedal has been treated as a single half pedal region common to the dampers of the individual keys without being distinguished among the dampers of the keys.
However, if it is assumed that such a half pedal region can differ among the dampers of the individual keys to be precise, a start point of the conventional common half pedal region can be considered to exist between a point when the first one of the dampers starts to be driven and a point when the last one of the dampers starts to be driven. Further, an end point of the conventional common half pedal region can be considered to exist between a point when the first one of the dampers gets out of contact with the corresponding string set and a point when the last one of the dampers gets out of contact with the corresponding string set.
As a matter of fact, the lifting rail elongated in a horizontal or left-right direction is supported at its portion connected with the pedal and cantilevered at the supported portion, so that flexural deformation may occur in the lifting rail and hence the lifting rail may not always extend in a complete horizontal direction. Therefore, strictly speaking, the lifting rail may undesirably differ in height position depending on its portions in the horizontal, left-right direction, and thus, the start and end points of the half pedal region may differ among the dampers of the individual keys.
Also, there may be undesirable variation in position and dimensions among the dampers of the individual keys. Further, resiliency of a damper lever felt interposed between the lifting rail and the damper lever as well as resiliency of the damper belt directly contacting the sting set would also influence the half pedal region. These factors would also cause the half pedal region to vary among the dampers of the individual keys.
In the case where the half pedal region differs among the dampers of the individual keys in the strict sense of the term, some of the dampers may actually start ascending at the start point of the half pedal region in response to depression of the pedal while others may not actually start ascending at the start point of the half pedal region in response to depression of the pedal.
Normally, in product shipment, positions and dimensions of component parts responsible for the half pedal region are adjusted so that variation in half pedal region among tone pitches can be minimized. However, perfect setting and adjustment of the component parts is not easy, and thus, it is not easy to allow the half pedal region to be completely the same among the dampers.
The aforementioned patent literatures do not disclose an idea of considering the half pedal region separately for each of the dampers of the keys, and, in fact, it is difficult to accurately identify the half pedal region separately for each of the keys responsive to an operation of the pedal. Although it is desirable to allow a half pedal region to be identified separately for each of the dampers of the keys in order to realize accurate tuning, no effective method for meeting this desire has been established yet.